Effects of modified fat clearance technique in the diagnosis of metastatic lymph nodes in the mesorectum of patients with rectal cancer / 中华消化外科杂志

ABSTRACT

Objective To investigate the number, distribution and metastatic rule of lymph nodes in the mesorectum of rectal cancer specimen after processing the recta] cancer specimen with modified fat clearance technique. Methods Sixty patients with mid-low rectal cancer who had been admitted to Peking University School of Ontology from 2003 to 2008 were assigned to test group. All the 60 patients who denied neo-adjuvant therapy were treated with total mesorectal excision, and the rectums resected were processed with the modified fat clearance technique. Rectums from another 50 patients with mid-low rectal cancer in control group were fixed in formalin solution for 24 hours. The mesorectum was divided into anterior, posterior, left and right quadrants, and each quadrant was further divided into upper, middle and lower parts. The numbers of lymph nodes harvested and metastatic rate of lymph nodes between the 2 groups were analyzed by t test and chi-square test. Results (1) The numbers of lymph nodes harvested in the test and control groups were 1436 and 525, with statistical difference between the 2 groups (t =- 12. 153, P <0.05). The number of small lymph nodes(diameter≤5 mm) harvested in test group was 985. (2) The numbers of lymph nodes harvested in the anterior, posterior and bilateral mesorectum were 125,696 and 615, respectively. The numbers of lymph nodes harvested in the upper, middle and lower part of the mesorectum were 395,534 and 507, respectively. The metastatic rate of lymph nodes in the upper part of the mesorectum was 18.5% (37/200), which was significantly lower than in the middle [43.5% (87/200)] and lower [38.0% (76/200)] part of the mesoreetum (X2= 9. 414, 6.406, P < 0.05). Two hundred metastatic lymph nodes in 33 patients were harvested, 48.0% (96/200) of which with a diameter of ≤ 5 mm. Twenty percent patients had their TNM stage changed after the retrieval of metastatic small lymph nodes. Conclusions Modified fat clearance technique significandy improves the retrieval of lymph nodes, and more small lymph nodes retrieved can increase the accuracy of staging. Rectal cancer cells have strong tendency to disseminate to the distal mesorectum. Adequate excision of the distal mesorectum is key in controlling the local recurrence.